The best response is to do absolutely nothing, he’s just a child throwing a temper tantrum. Now if the lob a she’ll over the border, then respond x 10.
Translation: The Norks want us to send them another check.
They must be getting hungrier over there and it doesn’t look like a good winter. Time to rattle the sabers. It must be tough to get to a state of war readiness against an enemy who becomes bellicose at the drop of a hat every other week. Maybe that’s the plan.
If doing absolutely nothing means not gearing up in case the threat is real, and retaliating after a bunch of folks are slaughtered for not being prepared, then I'm glad you're not in a command position....